scientific notation with plotmath superscripts in ggplot

scientific_10.R

scientific_10 <- function(x,suppress_ones=TRUE) {
    s <- scales::scientific_format()(x)
    ## substitute for exact zeros
    s[s=="0e+00"] <- "0"
    ## regex: [+]?  = "zero or one occurrences of '+'"
    s2 <- gsub("e[+]?", " %*% 10^", s )
    ## suppress 1 x
    if (suppress_ones) s2 <- gsub("1 %\\*% +","",s2)
    parse(text=s2)
}

## use scale_(x|y)_continuous(labels=scientific_10, ...)

## now with lat and long
library(ggplot2)

## too much repetition here ...
long_label <- function(x) {
  s <- sprintf("%d*degree*%s",
               x,ifelse(x==0,"",
                        ifelse(x<0,"W","E")))
  return(parse(text=s))
}

lat_label <- function(x) {
  s <- sprintf("%d*degree*%s",
               x,ifelse(x==0,"",
                        ifelse(x<0,"S","N")))
  return(parse(text=s))
}
ggplot(mtcars,aes(wt,mpg)) + geom_point() +
  scale_x_continuous(labels=long_label) +
  scale_y_continuous(labels=lat_label) +
  labs(x="Longitude",y="Latitude")